I have frequently heard people recommend doing texturing using vibrating carving tools--in particular, the Ryobi tool seems to be good for this. Unfortunately, this tool is fairly expensive, but worse, it is no longer made. To use it for texturing a bowl, you remove the carving blade and insert a cut off 16d nail, with a rounded off end. Last week John Jordan brought this up at a club demo, and one of our members went home and experimented with the idea.
Not having the Ryobi tool, he used an air-operated vibrating tool from Harbor Freight. This tool is intended for removing cemented gaskets, and it costs a little over $20. His results were very successful. He took a discarded, cracked, roughed-out bowl blank and played with it. After he sprayed it black and sanded it, the result came out looking like a hammered black iron band shrunk onto the bowl. I believe any effect obtainable with the Ryobi tool could be duplicated with this air tool. If you already have a compressor, the additional investment is quite low.
My other reason for bringing this up is that we had a recent thread on the topic of what to do with our failed bowls, posted by Denis Marier. I would like to add to the list. When you want to try out an idea, what better way than to pick up one of your rejects and put it to use? This can be anything, like the above texturing idea, something like a chatter tool, a finishing idea, or a method of filling cracks. And, I believe you will learn more, with less effort, by using up your junk bowls in this way, than by using ordinary scrapwood.
Additional comments, anyone?